The present invention relates to a two piece, swage type fastener including a pin and a collar with the collar adapted to be swaged into lock grooves on the pin and more particularly to swage type fasteners that have an optimized lock groove and crest design for use in a plurality of applications with a plurality of collars of different materials and strength. The optimized lock groove and crest design can be used in a plurality of applications due to the lock grooves and crests being able to receive swaged materials from collars made of different materials and strength during swage. A method of designing a fastener is also provided that has a lock groove and crest geometry that is optimized and is provided as a uniform construction for use in the plurality of applications with collars of different materials and strength.
Swage fasteners can be of a pull type or stump type. A typical swage type fastener includes a pin and a collar with the pull type fastener having a pin shank having a locking portion with lock grooves and a pull portion with pull grooves. The pull grooves are adapted to be gripped by matching teeth in chuck jaws of an installation tool having a swage anvil adapted to engage the collar whereby a relative axial force can be applied between the pin and collar to move the anvil over the collar to swage it into the lock grooves.
With respect to swage fasteners of the pull type, the pull portion is connected to the lock groove portion via a breakneck groove of reduced strength which is adapted to fracture at a preselected magnitude of axial tensile force greater than required to swage the collar whereby the pull portion, or pintail, will be severed and removed from the pin shank after completion of swaging. The breakneck groove is of sufficient strength to withstand the high tensile load for swaging and the pull grooves must be similarly of sufficient strength to accept the relative axial pull load applied by the engaged teeth of chuck jaws of the installation tool. This routinely requires that the pull portion be of a relatively large diameter so as to have sufficient material to provide the necessary size and strength for the breakneck groove and also to inhibit fracturing of the pull grooves instead of the breakneck groove.
A typical stump type fastener includes a pin and a collar that has a pin shank having a locking portion with lock grooves. The difference between a swage fastener of the pull type and the stump type is that the stump type does not have a pull portion with pull grooves. Also, in the stump type fastener system, an installation tool is used that has a swage anvil adapted to engage the collar to apply a relative axial force between the pin and collar to move the anvil over the collar to swage it into the lock grooves and a bucking member that is used to engage the pin head.
U.S. Pat. Nos. 6,325,582, 6,233,802, 5,125,778, 5,090,852, 5,049,016, 4,867,625, 4,813,834, 4,472,096, 4,221,152 and 4,208,943 were issued to the assignee of the present invention or a predecessor in interest. These patents all relate to various swage fastener designs and are representative of the art. In the prior art, a fastener was typically optimized for a particular collar for a particular application. Also, in the prior art, fasteners typically had a single grip range. A single grip range means that a fastener could fasten workpieces that have variations in thickness of {fraction (1/16)} of an inch.
The optimization technique employed by the present invention departs from the prior art practice of optimizing a fastener for a particular collar for a particular application. In the present invention, the lock groove and crest geometry is optimized for use in a plurality of applications wherein the lock grooves and crests are each provided with the longest width required for a specific application to provide the fastening system with satisfactory clamp and tensile loads and resistance to failure in the plurality of applications when the lock grooves are filled with various materials from different collars of various strengths. Also, the lock groove and crest geometry is of a uniform construction that is used in the plurality of applications that enables the lock grooves and crests for each pin diameter to be manufactured with tooling that uses a common lock groove and crest geometry. Such an approach reduces costs associated with the tooling.
Additionally, for each pin size, certain collars of different materials have about the same outside diameter so an installation tool with a uniform swage anvil geometry can be used to swage those collars of different materials into the lock grooves to install the swage type fastener in workpieces for shear, shear/tension, shear composite and shear/tension composite application. Such an approach reduces the costs associated with labor in exchanging a swage anvil in the tool that is used in such applications.
Furthermore, the fastener of the present invention has a double grip range. Double grip means that a fastener can fasten workpieces that vary in thickness up to xe2x85x9 of an inch. Such an approach increases the versatility of the fastener.
It is an object of the present invention to provide a swage type fastener having a pin member with a lock groove and crest geometry that is optimized that is capable of having collars of various materials and strength swaged into the lock grooves with the lock grooves and crests being of a uniform construction for each pin diameter for use in connection with collars of different materials and strength.
It is another object of the invention to provide a swage type fastener having a pin member with a lock groove and crest geometry that is optimized that is capable of having collars of various materials and strength swaged into the lock grooves wherein the various materials provide the fastener with different clamp and tensile loads for use in a plurality of applications.
It is yet another object of the invention to provide a swage type fastener having a pin member with a lock groove and crest geometry that is optimized that is capable of having collars of various materials and strength swaged into the lock grooves wherein certain collars have about the same outside diameter that enables a common installation tool having a swage anvil with a uniform swage cavity to be used to swage these collars of different materials into the lock grooves to install the swage type fastener in workpieces for shear, shear/tension, shear composite and shear/tension composite applications.
It is yet another object of the present invention to provide a swage type fastener that has a double grip range.
It is yet another object of the invention to provide a method of designing a swage type fastener with a lock groove and crest geometry that is optimized that is capable of having collars of various materials and strength swaged into the lock grooves wherein the various materials provide the fastener with different clamp and tensile loads for use in a plurality of applications.
Certain objects of the invention are achieved by a fastening system that includes a fastener, for securing a plurality of workpieces together, the fastening system having a pin member having a lock groove and crest geometry that is optimized. The optimized lock groove and crest geometry is adapted to receive swaged material from a plurality of collars of different materials and strengths for securing workpieces in different applications having different load requirements, wherein the lock grooves are provided with the longest width required for collars of lower strength for one application or greater strength for a second application and the crests are provided with the longest width required for collars of greater strength for the second application whereby the fastening system will provide satisfactory clamp and tensile loads and resistance to failure in the plurality of applications when the lock grooves are filled with collar materials of different strengths. Such an optimization results in an overall minimization of size and weight of the fasteners with lock grooves and crests of a uniform construction for use with collars of different materials and strength. The lock groove and crest geometry for the pin member is of a uniform construction that is used in the plurality of applications with one or more pin members of a common diameter. Certain collars of different strengths are provided with about the same outside diameter. Such a construction permits use of a common installation tool having a swage anvil with a uniform swage cavity that swages such collars of different strengths into the lock grooves of the pin member for installing the swage type fastener in workpieces for shear, shear/tension, shear composite and shear/tension composite applications.
Other objects of the invention are achieved by a method of designing a fastener to be used in a fastening system. The method includes obtaining the clamp and tensile load requirements for a plurality of applications, optimizing the lock groove geometry by providing the lock grooves with the longest width required for collars of lower strength for one application or greater strength for a second application and optimizing the crest geometry by providing the crests with the longest width required for collars of greater strength for the second application. This method permits standardizing the optimized lock groove and crest geometry for the pin member for use of the swage type fastener in a plurality of applications with one or more pin members of a common diameter. Also, certain collars of different strength materials are provided with about the same outside diameter that are adapted to be swaged into the lock grooves to provide the fastening system with satisfactory clamp and tensile loads and resistance to failure in shear, shear/tension, shear composite and shear/tension composite applications.
Swage type fasteners are used for a variety of different applications including the joining of workpieces of various types of materials with a predetermined clamp and tensile load. For example, in aircraft applications, the workpieces can be of a lightweight metal such as aluminum or can be made of composite materials. The swage type fastener of the present invention is particularly useful because it may be used in connection with fastening metallic workpieces, composite workpieces or combinations thereof. As such, the swage type fastener of this invention is particularly advantageous in that it can be used in a variety of applications due to the ability of the optimized lock grooves of the pin member to be filled with various materials of different collars.